Why Does JavaScript Concatenate Instead of Adding Numbers?

Concatenation Instead of Summation in Numerical Addition

In certain programming scenarios, attempting to sum two numerical values can result in an unexpected behavior where the numbers are concatenated instead of being added. This issue arises when the input values are treated as strings rather than numbers.

Consider the following JavaScript code:

Upon executing this code, you may encounter a peculiar outcome where 1 2 returns "12" instead of the expected "3". This occurs because the variables y and z are initially retrieved as strings from the HTML input fields. JavaScript interprets the concatenation operation ( ) differently for strings than it does for numbers.

To rectify this issue and ensure the addition of numerical values, it is necessary to explicitly convert the strings to numbers before performing the calculation. JavaScript provides a simple solution to achieve this using the " " (unary plus operator).

By prepending each string with " ", they are coerced into numerical values. This allows JavaScript to perform the desired addition operation, resulting in the correct sum of the numbers. Hence, the corrected code snippet would be:

This modification ensures that the input values are treated as numbers, preventing the concatenation issue and producing the appropriate sum.

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